Re: [PATCH 2/2] configs: Add generic qcom_tfa_optee_defconfig

Sumit Garg
2026-01-21T07:21:53Z

On Fri, Jan 16, 2026 at 06:46:16PM +0100, Casey Connolly wrote:
> Hi Sumit,
>
> (Top-posting since this thread is getting a bit busy)
>
> I'm not sure if Neil and I properly conveyed why we don't agree with your
> proposal here: essentially it is an inversion of logic. CONFIG_OPTEE doesn't
> indicate that the board IS running OP-TEE, it just builds in support for
> OP-TEE. In general U-Boot is trying to trend away from using kconfig to
> dictate behaviour in this way.

OP-TEE as TZ is an optional feature for any arm64 SoC. And even with
U-Boot SPL as the initial boot-loader you get to decide via a Kconfig
option whether to support OP-TEE or not. Similarly with TF-A BL31, you
have to specify "spd=opteed" during build time if OP-TEE is supported or
not. So indeed it's a build time configuration for firmware to support
OP-TEE or not.

>
> Adjacently, for Qualcomm support in U-Boot we are trying to improve upon the
> status quo: we don't do board-specific code, we limit hardcoding
> functionality or build-time configuration in favour of runtime checks as
> much as possible.

Not sure why you consider the OP-TEE feature being added here to be
board specific. It is rather extending the qcom_defconfig to support
OP-TEE based security features. For sure, we need to support similar
board agnostic config fragments to enable UEFI secure boot with EFI
runtime varibales based on OP-TEE RPMB storage.

>
> With that perspective in mind, I would much prefer that switching from QTEE
> to TF-A/OP-TEE on the rb3gen2 (or any other qcom board) not require flashing
> a bespoke U-Boot build, the same build should just work on both.

The bespoke U-Boot build is already required for QTEE based flows, see:
- qcm6490_defconfig
- qcs9100_defconfig
- qcom_ipq5424_mmc_defconfig
- so on..

vs

U-Boot build with OP-TEE flow:
- qcom_defconfig + OP-TEE config fragment

And the resulting u-boot.bin gets used as BL33 for fip.bin as shown
here [1].

[1] https://trustedfirmware-a.readthedocs.io/en/latest/plat/qti/rb3gen2.html

>
> There are several ways it might be possible to check for OP-TEE at runtime,
> arguably the simplest is the SMC call I proposed (which could be restricted
> to just kodiak),

This is going to be board specific logic and not scalable.

> the other idea that comes to mind is populating the x2
> register with a magic number when jumping to U-Boot, or even using the
> functionality already in place for passing data between bootloader stages
> (assuming the necessary bits are upstream in both projects).

Having a generic mechanism for passing data among bootloader stages is
the way to go here. Firmware handoff spec here [2] provides a good
reference for that. Although I don't see a specific bloblist tag which
can be used to detect OP-TEE presence.

Not sure why blocking this OP-TEE feature to be supported on Qcom
platforms is a good idea until that firmware handoff mechanism get's
realized on Qcom platforms. Also, even when the same U-Boot build can't
be used for both QTEE and OP-TEE.

[2] https://github.com/FirmwareHandoff/firmware_handoff

>
> You say that making that SMC call on QTEE is undefined behaviour, but surely
> it doesn't break stuff? I'd hope that simply seeing what happens would be
> enough to define it, maybe checking with the boot team too.

As I said it's going to be hit and trial approach using SMC calls which
isn't scalable.

>
> Your patch also mentions the EFI DT fixup protocol, but there is no
> corresponding code for that. iirc there are other DT changes needed for
> everything to work properly on rb3gen2 with OP-TEE, is the plan to get those
> changes done in such a way that the same DT will work with both OP-TEE and
> QTEE?

With OP-TEE, we would be booting Linux in EL2 and there is corresponding
DT work going on for QTEE with *_el2.dtso being added. So essentially
the plan is to reuse same DT with *_el2.dtso overlay which is
independent of whether OP-TEE or QTEE is running.

However, even without that we have a functional boot to shell system
that can be used for OP-TEE based use-cases development.

-Sumit

>
> - Casey
>
> On 1/16/26 13:17, Sumit Garg wrote:
> > On Fri, Jan 16, 2026 at 10:53:15AM +0100, Neil Armstrong wrote:
> > > On 1/16/26 08:53, Sumit Garg wrote:
> > > > On Fri, Jan 16, 2026 at 08:34:33AM +0100, Neil Armstrong wrote:
> > > > > On 1/16/26 07:57, Sumit Garg wrote:
> > > > > > On Thu, Jan 15, 2026 at 02:35:23PM +0100, Neil Armstrong wrote:
> > > > > > > On 1/15/26 14:27, Sumit Garg wrote:
> > > > > > > > On Thu, Jan 15, 2026 at 02:03:29PM +0100, Neil Armstrong wrote:
> > > > > > > > > On 1/15/26 13:25, Sumit Garg wrote:
> > > > > > > > > > + Jens (OP-TEE driver author in U-Boot)
> > > > > > > > > >
> > > > > > > > > > On Thu, Jan 15, 2026 at 11:49:49AM +0100, neil.armstrong@linaro.org wrote:
> > > > > > > > > > > On 1/15/26 07:10, Sumit Garg wrote:
> > > > > > > > > > > > On Wed, Jan 14, 2026 at 03:56:02PM +0100, Casey Connolly wrote:
> > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > > > On 09/01/2026 12:02, Sumit Garg wrote:
> > > > > > > > > > > > > > On Thu, Jan 08, 2026 at 05:41:42PM +0100, Casey Connolly wrote:
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > On 29/12/2025 12:43, Sumit Garg wrote:
> > > > > > > > > > > > > > > > From: Sumit Garg <sumit.garg@oss.qualcomm.com>
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Recently upstream TF-A/OP-TEE has started gaining support for Qcom
> > > > > > > > > > > > > > > > platforms. RB3Gen2 being the first one and more to come. U-Boot in
> > > > > > > > > > > > > > > > corresponding boot flow is packaged as a position independent executable.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > So, lets add a generic U-Boot defconfig for Qcom platforms to support
> > > > > > > > > > > > > > > > TF-A/OP-TEE based TrustZone stack. Build command:
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > $ make qcom_tfa_optee_defconfig
> > > > > > > > > > > > > > > > $ make -j`nproc` DEVICE_TREE=qcom/qcs6490-rb3gen2
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > This would be better suited as a config fragment rather than a new
> > > > > > > > > > > > > > > defconfig imo.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > That's fine with me to add it as a config fragment.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > But more importantly, enabling OPTEE support in U-Boot doesn't imply
> > > > > > > > > > > > > > > that it will be used, just that it's supported.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > There are real use-cases of OP-TEE in U-Boot for Qcom platforms like
> > > > > > > > > > > > > > secure EFI variables based on OP-TEE secure storage. Have a look here [1].
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > And sure there will be more such use-cases like fTPM, KASLR etc. can be
> > > > > > > > > > > > > > supported based on OP-TEE.
> > > > > > > > > > > > >
> > > > > > > > > > > > > I was referring literally to the fact that CONFIG_OPTEE being enabled
> > > > > > > > > > > > > doesn't imply that OP-TEE is running, it's faulty logic to assume that's
> > > > > > > > > > > > > the case and add nodes to the DT.
> > > > > > > > > > > >
> > > > > > > > > > > > I don't disagree here as having a runtime check is always a better
> > > > > > > > > > > > choice then a compile time config option. However, there isn't a common
> > > > > > > > > > > > info method from properietary firmware that says if QTEE is running
> > > > > > > > > > > > instead of OP-TEE.
> > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > > > I just checked and there is an SMC call that tells you the UUID for the
> > > > > > > > > > > > > trusted OS, referred to as OPTEE_SMC_CALL_GET_OS_UUID in U-Boot and
> > > > > > > > > > > > > OPTEE_ABI_CALL_GET_OS_UUID in OP-TEE. Presumably this identifies OP-TEE
> > > > > > > > > > > > > specifically.
> > > > > > > > > > > >
> > > > > > > > > > > > Also, we don't know how the QTEE will react to this OP-TEE specific SMC
> > > > > > > > > > > > call given it's different variants running on legacy and the newer SoCs.
> > > > > > > > > > > > So I would suggest to better gate OP-TEE presence behind a compile time
> > > > > > > > > > > > check only.
> > > > > > > > > > >
> > > > > > > > > > > So you say it's fine to add the optee node, and the driver will bail out if
> > > > > > > > > > > OPTEE is not present, but it's not good to call OPTEE_SMC_CALL_GET_OS_UUID
> > > > > > > > > > > in the fixup code to enable OPTEE only if present ?
> > > > > > > > > > >
> > > > > > > > > > > It's literally the same, my point in https://lore.kernel.org/all/b60d5ee7-fa27-4dc1-8a09-964912ec5654@linaro.org/
> > > > > > > > > > > was exactly that, just call OPTEE_SMC_CALL_GET_OS_UUID and add the OPTEE
> > > > > > > > > > > node only if present _AND_ if CONFIG_OPTEE is enabled.
> > > > > > > > > > >
> > > > > > > > > > > Move the CONFIG_OPTEE enable in a fragment and we're done, you will only
> > > > > > > > > > > select OPTEE explicitly on desired platforms, and won't run the naughty
> > > > > > > > > > > OPTEE_SMC_CALL_GET_OS_UUID on old crappy platforms.
> > > > > > > > > >
> > > > > > > > > > I am still trying to understand what benefit does invoking
> > > > > > > > > > OPTEE_SMC_CALL_GET_OS_UUID from platform code provides us. Surely it
> > > > > > > > > > can't be used to detect OP-TEE not present when QTEE is running due to
> > > > > > > > > > unknown behaviour with QTEE.
> > > > > > > > >
> > > > > > > > > Sorry but what exactly do you expect that will happen if you enable the OPTEE
> > > > > > > > > driver when running with QTEE ?
> > > > > > > >
> > > > > > > > The OP-TEE SMC calls are not at all supported with QTEE, so the expected
> > > > > > > > behaviour is undefined. IOW, the OP-TEE SMC ABI is not compatible with
> > > > > > > > QTEE. However, it's going to be hit and trial method to see what QTEE
> > > > > > > > responds to OP-TEE SMC calls. So it's not a reliable source of
> > > > > > > > information we can use to detect which TEE is present or not.
> > > > > > >
> > > > > > > So until we know, this change is a no go, we can't just add the /optee node
> > > > > > > and hope the person building uboot did the right thing.
> > > > > >
> > > > > > Not sure why you think Qualcomm platforms are special in this regards
> > > > > > when similar OP-TEE node additions based on CONFIG_OPTEE exist for other
> > > > > > platforms, see example here [1] [2] [3].
> > > > > >
> > > > > > The OP-TEE configs will surely be part of a separate config fragment and
> > > > > > I can add comments there for developer's awareness.
> > > > > >
> > > > > > [1] arch/arm/dts/imx8mm-u-boot.dtsi:10
> > > > > > [2] arch/arm/dts/imx8mn-u-boot.dtsi:10
> > > > > > [3] arch/arm/dts/imx8mp-u-boot.dtsi:11
> > > > > >
> > > > > > >
> > > > > > > I propose an alternate way, is to check for QTEE and then test for OPTEE.
> > > > > >
> > > > > > There are more combinations rather than just QTEE or OP-TEE as follows:
> > > > > > - Older targets have support for QSEECOM
> > > > > > - Newer targets with QTEE support
> > > > > > - Chrome targets without any TEE support
> > > > > > - IoT targets with OP-TEE support
> > > > > >
> > > > > > Do you have any particular mechanism in mind for detecting OP-TEE
> > > > > > presence at runtime? And surely that has to be well supported on variety
> > > > > > of SoC where U-Boot is supported as of now.
> > > > >
> > > > > OPTEE_SMC_CALL_GET_OS_UUID which works fine on like all the other ARM based
> > > > > platforms.
> > > >
> > > > Can you share at-least one example of other Arm based platform where this
> > > > SMC call is used to add OP-TEE DT node?
> > >
> > > AFAIK no other platforms does that, I never said it was a standard thing,
> > > I said it would be necessary to avoid messing with the qualcomm proprietary
> > > boot chain.
> > >
> > > >
> > > > >
> > > > > It's the only way, and only Qualcomm engineers can answer how to determine
> > > > > without any risk which TEE is running on the system.
> > > >
> > > > The fact that you keep ignoring my responses that OP-TEE SMC ABI is not
> > > > compatible with QTEE/QSEECOM SMC ABI is not going to change (see [1]).
> > > >
> > > > I am not sure why it's a blocker to use CONFIG_OPTEE for OP-TEE DT node
> > > > addition on Qcom platforms when the same criteria is being used for imx8*
> > > > platforms already.
> > >
> > > It is not, if the node is present the it's fine. I'm concerned by adding
> > > the node when CONFIG_OPTEE is enabled.
> > >
> > > Usually, the ARM64 platforms are shipped with a well-known or compatible
> > > boot chain like TF-A, and OPTEE is present or not. Those platforms
> > > will add the optee node knowing it can be present, and knowing other TEE
> > > won't crash if OPTEE_SMC_CALL_GET_OS_UUID is called.
> > >
> > > You propose the other way, adding the optee node when config is present,
> > > not knowing exactly if the current system has optee or a qualcomm proprietary
> > > TEE that could not survive a OPTEE_SMC_CALL_GET_OS_UUID call.
> >
> > Maybe I should have provided reference to the overall open boot stack [1]
> > early which is being planned for IoT platforms to begin with. The PR for
> > meta-qcom is here [2]. We are mostly waiting for the OEM only signing
> > feature for TZ image to be available in XBL_SEC such that any developer
> > can excercise that stack:
> >
> > PBL (ROM) -> XBL -> TF-A BL2 -> TF-A BL31 -> BL33 -> Linux kernel
> > |
> > --> OP-TEE as BL32
> >
> > TF-A and OP-TEE are going to be supported in a similar fashion on Qcom
> > platforms as any other ARM64 platform.
> >
> > [1] https://trustedfirmware-a.readthedocs.io/en/latest/plat/qti/rb3gen2.html
> > [2] https://github.com/qualcomm-linux/meta-qcom/pull/1172
> >
> > >
> > > So my suggestion is:
> > > - ask the boot team a sequence/way to determine exactly which TEE is loaded (using SMC, smem or whatever)
> > > - only add the optee node if OPTEE or a compatible TEE is present
> > >
> > > Then if CONFIG_OPTEE is enabled & the node is present the driver will
> > > be able to communicate with OPTEE.
> >
> > Hence, OP-TEE is going to be supported in a developer controlled
> > environment only like any other ARM64 platform. So there is intention to
> > reuse the same workflows here. Since it's an open source boot stack then
> > it should be possible to use generic methodology if community comes up
> > with that later in future. That's why we should avoid Qcom specifc
> > platform code to enable such a feature apart from what others do.
> >
> > -Sumit
> >
> > >
> > > >
> > > > [1] https://lore.kernel.org/all/aWjrLF9DUPTaSA1c@sumit-xelite/.
> > > >
> > > > -Sumit
> > > >
> > > > >
> > > > > Without this, all this discussions is pointless.
> > > > >
> > > > > >
> > > > > > Also, there is added complexity for targets where the developer can't
> > > > > > change the TZ firmware themselves on Qcom SoCs due to QTI signing
> > > > > > requirement.
> > > > > >
> > > > > > -Sumit
> > > > > >
> > > > > > >
> > > > > > > Neil
> > > > > > >
> > > > > > > >
> > > > > > > > -Sumit
> > > > > > > >
> > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > Jens,
> > > > > > > > > >
> > > > > > > > > > Will it be fine with you to expose is_optee_api() from the OP-TEE driver
> > > > > > > > > > for the platform code to invoke it independently? Just for the sake of this
> > > > > > > > > > discussion in case people still insist on it being the right thing to do.
> > > > > > > > > >
> > > > > > > > > > -Sumit
> > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > Neil
> > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > > > My suggestion would be to make this SMC call if CONFIG_OPTEE is enabled
> > > > > > > > > > > > > in qcom_psci_fixup(), compare the UUID and add the node if it matches.
> > > > > > > > > > > >
> > > > > > > > > > > > That's exactly the first SMC call that U-Boot and Linux OP-TEE driver
> > > > > > > > > > > > does to compare the UUID here [1] and bail out of the driver. I don't
> > > > > > > > > > > > see a value of a redundant invoke in the Qcom specific platform code.
> > > > > > > > > > > >
> > > > > > > > > > > > [1] drivers/tee/optee/core.c:823: if (!is_optee_api(pdata->invoke_fn))
> > > > > > > > > > > >
> > > > > > > > > > > > -Sumit
> > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > [1] lib/efi_loader/efi_variable_tee.c
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > So I think the more appropriate patch here would be to just enable
> > > > > > > > > > > > > > > OP-TEE in qcom_defconfig (assuming the binary size isn't significantly
> > > > > > > > > > > > > > > affected).
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > The OP-TEE driver in U-Boot itself is probed based on DT and it's not
> > > > > > > > > > > > > > only specific to Qcom platforms but every other platform using OP-TEE.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Considering the other patch is based on this assumption that if OP-TEE
> > > > > > > > > > > > > > > support is enabled then the board must be using it, a different approach
> > > > > > > > > > > > > > > is definitely needed.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Yeah that's true even with TF-A boot flow, there is possibility to boot
> > > > > > > > > > > > > > without OP-TEE as well. However, TF-A generally doesn't provide a
> > > > > > > > > > > > > > generic option to detect whether OP-TEE is running or not.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > When I was looking into this last year I remember discussing this same
> > > > > > > > > > > > > > > issue from the Linux side, there is a good argument to be made that
> > > > > > > > > > > > > > > OP-TEE support in Linux shouldn't be based on the devicetree -
> > > > > > > > > > > > > > > particularly in the Qualcomm case where whether or not OP-TEE is used is
> > > > > > > > > > > > > > > a simple software change, nothing to do with hardware.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Sadly it's true for every other silicon vendor too. But OP-TEE support
> > > > > > > > > > > > > > based on DT has become an ABI unless migration for OP-TEE support based
> > > > > > > > > > > > > > on FF-A comes into picture.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > So in general I'm not particularly keen on this approach, I think it
> > > > > > > > > > > > > > > /might/ be acceptable for U-Boot to have some fixup code to add the
> > > > > > > > > > > > > > > OP-TEE node if OP-TEE is in use with the idea of phasing that out in
> > > > > > > > > > > > > > > favour of runtime detection in the OS itself. I'd also expect that fixup
> > > > > > > > > > > > > > > code to go in the generic U-Boot DT fixup code that runs before we jump
> > > > > > > > > > > > > > > to the OS (like the EFI DT fixup function).
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > The EFI DT fixup code is already there based on U-Boot DT. Have a look
> > > > > > > > > > > > > > here:
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > boot/image-fdt.c:627: fdt_ret = optee_copy_fdt_nodes(blob);
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > In general on Arm platforms there isn't any SMC bus to detect
> > > > > > > > > > > > > > dynamically if there is support for OP-TEE or not. That's why
> > > > > > > > > > > > > > platform bus was choosen for the U-Boot and Linux OP-TEE driver. It's
> > > > > > > > > > > > > > similar to how we have the SCM DT node for Qcom platforms.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > FF-A bus tries to solve that problem to unify that approach for future
> > > > > > > > > > > > > > platform but U-Boot hasn't yet gained support for FF-A based OP-TEE
> > > > > > > > > > > > > > driver too.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Anyhow, this is the sanest way I can come up with to enable OP-TEE
> > > > > > > > > > > > > > support in a general way for all the Qcom platforms. This is aligned
> > > > > > > > > > > > > > with how OP-TEE support is detected for other silicon vendors too.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > -Sumit
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Kind regards,
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > For more information refer here:
> > > > > > > > > > > > > > > > https://trustedfirmware-a.readthedocs.io/en/latest/plat/qti/rb3gen2.html
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Signed-off-by: Sumit Garg <sumit.garg@oss.qualcomm.com>
> > > > > > > > > > > > > > > > ---
> > > > > > > > > > > > > > > > configs/qcom_tfa_optee_defconfig | 7 +++++++
> > > > > > > > > > > > > > > > 1 file changed, 7 insertions(+)
> > > > > > > > > > > > > > > > create mode 100644 configs/qcom_tfa_optee_defconfig
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > diff --git a/configs/qcom_tfa_optee_defconfig b/configs/qcom_tfa_optee_defconfig
> > > > > > > > > > > > > > > > new file mode 100644
> > > > > > > > > > > > > > > > index 00000000000..c398521770f
> > > > > > > > > > > > > > > > --- /dev/null
> > > > > > > > > > > > > > > > +++ b/configs/qcom_tfa_optee_defconfig
> > > > > > > > > > > > > > > > @@ -0,0 +1,7 @@
> > > > > > > > > > > > > > > > +# Configuration for building a generic U-Boot image
> > > > > > > > > > > > > > > > +# with support for TF-A/OP-TEE based Arm TrustZone stack.
> > > > > > > > > > > > > > > > +
> > > > > > > > > > > > > > > > +#include "qcom_defconfig"
> > > > > > > > > > > > > > > > +
> > > > > > > > > > > > > > > > +CONFIG_TEE=y
> > > > > > > > > > > > > > > > +CONFIG_OPTEE=y
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > --
> > > > > > > > > > > > > > > // Casey (she/her)
> > > > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > > > --
> > > > > > > > > > > > > // Casey (she/her)
> > > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > >
> > > > > > >
> > > > >
> > >
>